Use Feedback

The user should receive immediate and tangible feedback during interaction
with an application. Appropriate feedback includes acknowledging a request,
pointing out an error, or tracking the progress of an operation. Although auditory
feedback can be useful for attracting a user's attention, it should be used
sparingly in a pen-based application for the following reasons:

Many users find beeps annoying.

Pen-based computers will be used more and more frequently in conference rooms
and other group areas where beeping from a machine will not be welcome.

Auditory messages disappear without a trace. If the user is momentarily away
or distracted, the auditory signal has failed to do its job.

If the user can turn the warning sound off, sound is not a reliable source of
feedback.

An audible notification is not useful for users who are deaf or hard of
hearing.